1988 Penny Circle Anomaly?

Whoa guys lets just call it a UFO and leave.

I didn't think this through, you're right, it's not PMD, my bad. I was thinking of other times where we called PMD unknowns ufos. I was wrong, sorry.

This was quite the discussion. It's part of the reason I enjoy this forum. People are so much alike and yet so often different with their opinions. Ranging from PMD, to die issue. From lathe markings to UFO.
In the end I think you have a coin with issues that do not surface often enough for there to be one definitive explanation. Such as a RPM. So that initiates thought, and discussion, and debate, which only helps in our learning and understanding of what intrigues us in this hobby.
Great post.
Great responses.

Cudos to Merclover for her acknowledging an oversight and her apology in the post.
Thanks all.

Its not PMD but nobody ever came up with a solution on what causes them. Here's a good link but since then, many more have surface on different denominations.
http://www.error-ref.com/tiny-circl...and-spirals/

I still believe its something to do with lathe lines

Your scenario may have some merit. However, the rings vary quite a bit in size and are often not perfectly centered. While some form a smooth circle or semicircle, others are somewhat irregular or have irregular features extending from the main ring. Paired, concentric rings are sometimes seen. Given their variability, it's entirely possible that these die rings stem from more than one cause.

I have had a lot of time to think about this circle on the 1988-P cent. Now for all the people who said it was POST MINT DAMAGE you are really not that smart and probably should go rethink what you actually know about coins. Post Mint Damage will always take away from the coin almost 100% of the time. If this was PMD the coin would be wrecked adding metal to a coin is extremely difficult and will always be seen especially as close as the one picture I posted got. It is clearly obvious this was on the die when it was struck. Now how it got there that is the magic question.
Here is a page on https://www.error-ref.com/?s=1988+circle that references it. It shows a pic of one just like mine showing there are multiple out there. Error-ref dot com is a great website of everything you can think of that is on coins, could happen to them and anything you can find good and bad. So anyone new when they tell you post mint damage or Machine Doubling keep the coin, do more research and you will find out the answer.

Excellent coin, congrats on the find, and I even re-read the whole thread.

BTW-That is the same link John1 shared back on page 1(?) and the coin in the link is the same as yours.